Polishing means



Aug. 15, 1939. I F. HbLLSTIN 9,

POLISHING MEANS Filed Dec. 5, 1937 2 Sheets-Sheet 1 Egg. 2.

Fgg. 1. I

.ulllll/ INVENTOR FRA/vz HdLL s TIN A- ATTORNE S Aug. 15, 1939. b Ls'n2,169,841

POLISHING MEANS Filed Dec. 3, 1937 2 Sheets-Sheet 2 iiljllllllplmlllijljljiw INVFN'FOR FRANZ HOLLSTIN ATTORNEYS V Patented Aug.'1 5, 1933UNITED STATES POLISHING MEAN S Franz Hiillstin, Berlin, Germany,assignor to Rheinmetall-Borsig Aktiengesellschaft Werk BorsigBerlin-Tegel, Berlin-Tegel, Germany Application December 3, 1937, SerialNo. 177,881

, In Germany September 29, 1936 4 Claims. -(Cl. 51- 31) Figure 3 is across-section along the line 3-3 This invention relates to polishingmeans, and

refers more particularly to a device for polishing spiral elongatedgrooves situated upon the inner walls of a hollow body.

when the grooves of this type are bored, for example in the manufactureof rifles and machine-guns, the cutter making these grooves often leavesan uneven surface, due tow-shifting in the course of the manufacturSmall cracks or depressions are formed in the grooves, which must beremoved later by polishing means, as otherwise the article cannot beused; grooves of this type should be extremely smooth, clean, andregular, particularly if the articles manui factured are the barrels offirearms, such as rifles or machine guns.

Attempts to satisfy these requirements through the use of polishingbodies movable within the hollowarticle and consisting of siliconcarbide or the like have been unsuccessful, since the polishing mediumis collected in the small crevices and cracks, and due to the movementsof the silicon carbide body forms additional grooves or unevennesseswhich often extend along the entire work piece.

An object of the present invention is the provision of means through theuse of which it is possible to produce grooves situated in a hollowbodywhich are extremely smooth, uniform, and

, well polished. v

Another object is the provision of means which are simple inconstruction and which can be used without increasing the usual timerequired for polishing, for eliminating the crevices and cracksformed-by the cutter while cutting inner spiral grooves within a hollowbody.

A further object is the provision of means for permanently andsatisfactorily removing unevennesses 'in' inner 'grooves within acomparatively short time. p

The above and other objects of the present invention may be realized bymoving the polishing tool longitudinally in the direction of the,

grooves and at the same time causing the work piece to carry out anoscillating or turning movement, both these movements taking placesimultaneously in the course of the polishing process.

The invention will appear more clearly from the following detaileddescription when taken in connection with the accompanying drawings,showing byway of example a preferred embodiment of the inventive idea.

In the drawings:

Figure l is a side elevation of a polishing machine constructed inaccordance with the principles of the present invention; T

Figure 2 is a detailed section showing the position of thepolishing-tool within the article to be polished;

of Figure 2;

Figure 4 is'a horizontal section along the line 4-4 of Figure 1;

Figure 5 shows the machine'in side elevation, looking in the directionof the arrow 5 in Figure 1; and

Figure 6 is a section-along the line 6-6 of Figure 1.

The machine illustrated in the drawings comprises a vertical machineframe I 8, which is carried by the legs 19. The frame l8 comprises anupper plate 20 carrying two guides'2l and 22. The guides 2| and 22,which are similar to each other in form, are provided with. openingsthrough which the two spindles 23 and. 24 extend.

The spindles 23 and 24 are also similar to each other and are providedwith elongated spiral outer grooves 25, which correspond to the groovesformed in the work pieces I0. The guides 21 and 22 are provided withprojections (not shown) which are situated within the bore-holes ofthese guides and which engage the grooves 25 of the spindles 23 and 24.

The inner walls of the machine frame l8 are provided with guides 26 and21 engaging a carriage B, which is vertically reciprocated along theguides 26 and 21 and which carries thesupports 8 and 40 for the spindles23 and 24, respectively.

The carriage 6 carries a pivot 28, upon which is mounted one end of arod 29. The lower end of the rod 29 is mounted upon a pin 30 carried bya wheel l3. .An endless belt 3| passes over the wheel I3 and also over apulley 32, which is rotatable along with the shaft 33 of a motor 34. Dueto this arrangement, the carriage 6 along with the spindles 23 and 24 isvertically reciprocated when the motor 34 is running.

The tools used for polishing the manufactured work pieces consist ofelongated rods 9 carrying cylinders l I, provided with spiralprojections the curvature of which corresponds to the curvature of thegrooves 1 within the work pieces Ill. The tools 9 are inserted into theheads 8 carried by the carriage 6 in such manner that they not onlyreciprocate vertically along with the carriage 6, and the spindles 23and 24, but also rotate along with these spindles 23 and24. This deviceis of standard construction and is not shown further in the drawings.

As already state, the curvature of the spiral grooves l in theworkpieces Ill corresponds to the curvature of the grooves 25 in thespindles 23 and 24. The projections vl2 of the polishing cylinders llmove, therefore, within the grooves 1 in the course of the combinedreciprocatory and rotary movementof the spindles 23 and 24 and the tools9. a

The polishing cylinder ll of a-polishing tool 9 is shown in detail inFigures 2 and 3 of the drawlogs. The curvature of the spiral projectionsl2 of this cylinder corresponds to that of the grooves I of the workpiece I0,.but the width of these projections I2 is equal to only aboutone third of the width of the grooves 1.

As is customary in the art, the polishing cylinder H may be formed by alead casting corresponding to the interior of the work piece It! andcarried by a rod 9.

If barrels of firearms are to be manufactured in this manner, it isnecessary to provide different cylinders for barrels of difierent sizesand forms.

Figures 2 and 3 show the position of the polishing cylinder ll withinthe work piece I!) .when the machine is ready to be started. Thepolishing tools 9 are mounted within the supports 8 and 4D in suchmanner that the ribs I2 of the cylinders H extend substantially in themiddle of the grooves I of the work pieces l0 (Figure 3).

A pulley I6 is in frictional engagement with a surface 35 of the wheeli3, so that the pulley is rotated by the wheel Ill.

The work pieces 10 are mounted in cylindrical supports i4 and 33, whichare rotatable around their vertical axis and which are carried by abracket I'I integral with the frame ill of the machine. The wheel I6 isconnected with one end of a driving rod 36, which is pivotally connectedat 31 with the cylinder 38. The cylinder 14 is connected with thecylinder 38 by a con necting rod 39.

The device operates as follows:

When the motor 34 is started, the endless belt 3| will rotate the wheell3 which carries one end of the rod 29. The rod 29 will reciprocate thecarriage 6 in the vertical direction along the guides 23 and 21. Sincethe spindles 23 and 24 are rotatably mounted in the supports 8'and 40carried by the carriage 6, and since the grooves 25 of the spindles 23and 24 are in engagement with corresponding projections formed withinthe guides 2| and 22, the spindles 23 and 24 will not only reciprocatealong with the carriage 6 but will rotate around their longitudinalaxis.

Since the tools 9 are firmly connected with the spindles 23 and 24, theywill carry out the same movement as these spindles, namely, they willreciprocate .vertically and also rotate.

At the same time, thepulley i6, which is in frictional engagement withthe surface 35 of the wheel l3, will be rotated by the wheel l3. The rod36, which is connected with the wheel l6 and the supports l4 and 38,will transform this rotation of the pulley l6 into an oscillatorymovement of the work piece supports l4 and 38 around their verticalaxis. Since the work pieces l0 are firmly mounted within their suportsl4 and 38, they will oscillate along with them.

The position of the rod 33 relatively to the pulley I6 may be soadjusted that the extent of the oscillatory movement of the work piecesID will be equal to the width of a groove I of the work piece minus thewidth of a projection l2 of the polishing cylinder ll.

.Due to this oscillatory movement of the work pieces the dust formed bythe polishing means is prevented from collecting in the small crevicesand cracks of the work piece, so that these particles will not increasethe uneven portions of the article, and the crevices and cracks willdisa pear very quickly.

This invention is of particular advantage in the manufacture of barrelsfor firearms, since it makes it possible to eliminate unevennesses in anextremely short time and with exact precision.

Obviously, diflferent means may be used for causing the movement of thework piece or'the polishing tool in the course of the polishing process,for example, if necessary, the polishing tool 9 may carry out anoscillatory movement while the work piece I!) may be verticallyreciprocated.

It is also possible to cause the polishing tool ll to carry out bothmovements.

struction without departing from the scope or intent of the invention,and all of such variation and modifications are to be included withinthe scope of the present invention. 1

What is claimed is:

1. A device for polishing inner spiral grooves of a hollow body, saiddevice comprising a polishing tool having projections extending in thedirection of said grooves and adapted to be situated within saidgrooves, and means for causing a relative movement between saidpolishing tool and the hollow body in the direction of the longitudinalaxis of said grooves, and for causing during said longitudinal movementa continuous relative oscillatory movement of substantially smallamplitude between said polishing tool and the hollow body around saidlongitudinal axis.

2. A device for polishing inner spiral grooves of a hollow body, saiddevice comprising a polishing tool having projections extending in thedirection of said grooves and adapted to be situated within saidgrooves, reciprocating means connected with said polishing tool formoving I said polishing tool relatively to said hollow body in thedirection of; the longitudinal axis of said grooves, a rotary wheel,means operatively connecting the first-mentioned means with said wheel,another wheel which is in frictional contact with the first-mentionedwheel, and means driven by the second-mentioned wheel and connected withsaid hollow body for simultaneously oscillating it with a substantiallysmall amplitude around said longitudinal axis.

3. A device for polishing inner spiral grooves of a hollow body, saiddevice comprising a polishing tool having projections the width of whichis equal to about one third of the width of said grooves, saidprojections being adapted to be situated within said grooves, means forcausing a relative movement between said polishing tool and the hollowbody in the direction of the longitudinal axis of said grooves, andmeans for causing a continuous relative oscillatory movement ofsubstantially small amplitude between said polishing tool and the hollowbody around said longitudinal axis during said longitudinal movement.

4. A device for polishing inner spiral grooves of a hollow body, saiddevice comprising a polishing tool having projections extending in thedirection of said grooves and adapted to be situated within saidgrooves, means connected with said polishing tool for reciprocating saidpolishing tool relatively to said hollow body in the direction of thelongitudinal axis of said grooves, means engaging said. polishing toolfor simultaneously oscillating it around its longitudinal axis, andmeans driven by the first-mentioned means for continuously oscillatingsaid hollow body simultaneously with the reciprocating movement with asubstantially small amplitude around the longitudinal axis of saidgrooves.

FRANZ Homs'rm.

